> do you suggest SaaS businesses should reject those customers who prefer paying with prepaid cards

Not the parent, but: yes, absolutely. Prepaid cards are for making one-time payments. They are not suitable for setting up ongoing subscriptions, and it is entirely appropriate for a merchant to reject them in this context.

> Prepaid cards are for making one-time payments. They are not suitable for setting up ongoing subscriptions

Why? Because from the point of the view of the customer, they are the best fit for that purpose.

> Because from the point of the view of the customer

From the point of view of a legitimate customer who intends to pay for a service, a prepaid card is a poor fit for an ongoing subscription, as it will stop working unpredictably when its funds are exhausted (causing it to start rejecting all charges).

Optimizing for customers who intend to ditch a service without paying for it is not a goal.

I'm sorry, but this makes no sense at all. The only difference between these two scenarios is who is in a position of power. If I use a prepaid card, it's not because I intend to ditch a service, but to control the costs.

A simple example of one of the services I use, Mailerlite. When the funds are depleted, I receive an email from them they were unable to charge me this month and they downgraded me to their free plan, and they will try again in two days. I then charge my card, they charge me and everything is fine. You don't want people like me - fine, you will have less customers. And I'm a very loyal customer, cases like failed payment happen maybe once 2-3 years.